Inks for 3D printing having low polymerization shrinkage

ABSTRACT

In one aspect, inks for use with a three-dimensional (3D) printing system are described herein. In some embodiments, an ink described herein comprises 20-60 wt. % oligomeric curable material; 10-50 wt. % cyclocarbonate (meth)acrylate monomer; and 0.1-5 wt. % photoinitiator, based on the total weight of the ink. Additionally, in some cases, the ink further comprises one or more additional curable materials differing from the oligomeric curable material and the cyclocarbonate (meth)acrylate monomer. An ink described herein, in some embodiments, also comprises one or more additional component that are non-curable.

RELATED APPLICATION DATA

The present application claims priority pursuant to 35 U.S.C. § 119(e)to U.S. Provisional Patent Application Ser. No. 62/773,370 filed Nov.30, 2018, which is incorporated herein by reference in its entirety.

FIELD

The present invention relates to inks for use with three-dimensional(3D) printing systems.

BACKGROUND

Some commercially available 3D printers or additive manufacturingsystems, such as the Projet™ 3D Printers manufactured by 3D Systems ofRock Hill, S.C., use inks, which are also known as build materials, thatare jetted through a print head as a liquid to form various 3D objects,articles, or parts. Other 3D printing systems also use an ink that isjetted through a print head or otherwise dispensed onto a substrate. Insome instances, the ink is solid at ambient temperatures and converts toliquid at elevated jetting temperatures. In other instances, the ink isliquid at ambient temperatures. Moreover, in some cases, the ink can becured following dispensing and/or deposition of the ink onto thesubstrate. Curing can be achieved using a laser or other source ofelectromagnetic radiation.

Other 3D printers form 3D articles from a reservoir, vat, or containerof a fluid ink or build material or a powdered ink or build material. Insome cases, a binder material or a laser or other source is used toselectively solidify or consolidate layers of the ink or build materialin a stepwise fashion to provide the 3D article.

Many inks used in additive manufacturing include (meth)acrylates as amajor or primary component. However, polymerization of (meth)acrylates,including light-induced polymerization such as occurs duringphotocuring, can result in volumetric polymerization shrinkage of theink. This volumetric shrinkage can limit the use of (meth)acrylates invarious additive manufacturing systems. This shrinkage can also reduceprinting resolution and/or fidelity of the printed article to thedesired geometry (e.g., with reference to the relevant computer aideddesign (CAD) parameters associated with the article). Moreover, manyprevious (meth)acrylate-based inks have lower notched impact strengthand/or tear strength than desired for some applications.

Therefore, there exists a need for improved methods and inks for 3Dprinting that have improved volumetric polymerization shrinkageproperties, improved printing resolution/fidelity, and/or improvedstrength (e.g., tear strength). A need also exists for inks that canprovide one or more of the foregoing properties while also allowingother properties to be modified as desired by the use of additionalcomponents, other than the primary curable components of the inks.

SUMMARY

In one aspect, inks for use with a 3D printer are described herein,which, in some embodiments, may offer one or more advantages over priorinks, particularly (meth)acrylate-containing inks for use in additivemanufacturing. For example, inks described herein can be used to printarticles with reduced or improved volumetric polymerization shrinkage.Inks described herein can also be used to print articles with improvedaccuracy and/or precision. Additionally, inks described herein, in somecases, can be used to form articles having a poly(meth)acrylate networkand also having improved impact strength and/or tear strength, whencompared to other articles formed from other (meth)acrylate inks notaccording to the present invention. Further, inks described herein, insome embodiments, provide one or more of the foregoing advantageswithout sacrificing speed of the additive manufacturing process.Moreover, inks described herein can be used in a variety of different 3Dprinters or additive manufacturing systems, such as those based onStereolithography (SLA), Digital Light Processing (DLP), and Multi-JetPrinting (MJP).

In some embodiments, an ink for use in a 3D printing system describedherein comprises 20-60 wt. % oligomeric curable material; 10-50 wt. %cyclocarbonate (meth)acrylate monomer; and 0.1-5 wt. % photoinitiator,based on the total weight of the ink. Additionally, in some cases, theink further comprises one or more additional curable materials differingfrom the oligomeric curable material and the cyclocarbonate(meth)acrylate monomer. An ink described herein, in some embodiments,also comprises one or more additional component that are non-curable.For instance, in some cases, an ink described herein further comprisesat least one colorant, at least one filler, at least one inhibitor, atleast one stabilizing agent, or a combination of two or more of theforegoing. It is to be understood, of course, that the total amount ofthe oligomeric curable material, cyclocarbonate (meth)acrylate monomer,photoinitiator, additional curable material (if present), and one ormore additional non-curable components (if present) is equal to 100 wt.% (for a given ink).

Moreover, in general, the oligomeric curable material of an inkdescribed herein comprises one or more ethylenically unsaturated specieshaving a molecular weight (e.g., a weight average molecular weight) of500-6,000. Further, in some instances, the oligomeric curable materialcomprises one or more ethylenically unsaturated species having a dynamicviscosity of 1,000 to 250,000 cP or 1,000 to 200,000 cP at 50° C., whenmeasured according to ASTM D2983. In some cases, the oligomeric curablematerial comprises one or more aliphatic urethane (meth)acrylates.Moreover, in some preferred embodiments, the oligomeric curable materialis present in the ink in an amount of 25-50 wt. %, based on the totalweight of the ink.

In addition, the cyclocarbonate (meth)acrylate monomer of an inkdescribed herein generally has the structure of Formula (A1):

wherein R₁ is selected from the group consisting of a linear or branchedC1-C6 alkylene moiety, a C1-C4 alkylene moiety, an alkylene-carbonatemoiety, an alkylene-ester moiety, and an alkylene-amide moiety; andwherein R₂ is H or CH₃. For reference purposes herein, it is to beunderstood that a “Cn-Cm alkylene moiety” (e.g., a “C1-C6 alkylenemoiety”) is a bivalent saturated aliphatic radical having from “n” to“m” carbon atoms (e.g., 1 to 6 carbon atoms, and no more than 6 carbonatoms). In some preferred embodiments, R₁ is CH₂ and R₂ is H. Moreover,in some preferred embodiments, the cyclocarbonate (meth)acrylate monomeris present in the ink in an amount of 10-50 wt. %, 15-50 wt. %, 15-35wt. %, or 20-30 wt. %, based on the total weight of the ink.

As noted above, an ink described herein, in some cases, furthercomprises one or more additional curable materials differing from theoligomeric curable material and the cyclocarbonate (meth)acrylatemonomer. In some instances, for example, the additional curablematerials comprise an additional monomeric curable material and/or anadditional oligomeric curable material, as described furtherhereinbelow.

Additionally, it is to be understood that the photoinitiator of an inkdescribed herein is operable to initiate curing of the oligomericcurable material, the cyclocarbonate (meth)acrylate monomer, and theadditional curable material(s) (if present), when the photoinitiator isexposed to incident curing radiation.

It is further to be understood that an ink described herein, in eitherthe uncured state or the cured state, can have one or more structuralproperties that provide an advantage for use of the ink in additivemanufacturing. For example, in some embodiments, the dynamic viscosityof an uncured ink described herein is greater than 100 cP at 25° C.,when measured according to ASTM D2983. In some embodiments, the dynamicviscosity of an uncured ink described herein is greater than 100 cP andless than 5000 cP at 25° C., when measured according to ASTM D2983.Similarly, in other cases, an ink described herein, when cured, exhibitsa volumetric polymerization shrinkage of no greater than 5% compared tothe ink when uncured, wherein the volumetric polymerization shrinkage ismeasured according to ASTM D792. Further, in some instances, an ink,when cured, exhibits a notched Izod impact strength of 50 to 200 J/mwhen measured according to ASTM D256 and/or a tear strength of 20 to 200kN/m when measured according to ASTM D624.

In another aspect, methods of forming a 3D article by additivemanufacturing are described herein. In some embodiments, such a methodcomprises selectively depositing layers of an ink described herein in afluid state onto a substrate to form the three-dimensional article. Themethod can further comprise photocuring the ink. Additionally, in someembodiments of a method described herein, the ink is selectivelyphotocured according to preselected computer aided design (CAD)parameters.

Alternatively, in other embodiments, a method of forming a 3D article byadditive manufacturing comprises retaining an ink described herein in afluid state in a container, and selectively applying energy to the inkin the container to solidify at least a portion of a first fluid layerof the ink, thereby forming a first solidified layer that defines afirst cross-section of the article. The method further comprises raisingor lowering the first solidified layer to provide a second fluid layerof the ink at a surface of the fluid ink in the container, andselectively applying energy to the ink in the container to solidify atleast a portion of the second fluid layer of the ink, thereby forming asecond solidified layer that defines a second cross-section of thearticle, the first cross-section and the second cross-section beingbonded to one another in a z-direction. As described furtherhereinbelow, the foregoing steps may be repeated any desired number oftimes needed to complete the 3D article. Moreover, in some preferredembodiments, selectively applying energy to the ink in the containercomprises photocuring the ink. In addition, in some cases, a method ofprinting described herein has a print speed of 40-60 mm/min, such as 50mm/min.

In still another aspect, printed 3D articles are described herein. Suchan article can be formed from any ink and using any method describedherein. Such printed 3D articles, in some cases, have superior accuracyand/or toughness (e.g., tear strength) compared to some other 3Darticles, particularly when formed primarily from a poly(meth)acrylatepolymer network.

These and other embodiments are described in greater detail in thedetailed description which follows.

DETAILED DESCRIPTION

Embodiments described herein can be understood more readily by referenceto the following detailed description and examples. Elements, apparatusand methods described herein, however, are not limited to the specificembodiments presented in the detailed description and examples. Itshould be recognized that these embodiments are merely illustrative ofthe principles of the present disclosure. Numerous modifications andadaptations will be readily apparent to those of skill in the artwithout departing from the spirit and scope of the disclosure.

In addition, all ranges disclosed herein are to be understood toencompass any and all subranges subsumed therein. For example, a statedrange of “1.0 to 10.0” should be considered to include any and allsubranges beginning with a minimum value of 1.0 or more and ending witha maximum value of 10.0 or less, e.g., 1.0 to 5.3, or 4.7 to 10.0, or3.6 to 7.9. Similarly, a stated range of “1 to 10” should be consideredto include any and all subranges beginning with a minimum value of 1 ormore and ending with a maximum value of 10 or less, e.g., 1 to 5, or 4to 10, or 3 to 7, or 5 to 8.

All ranges disclosed herein are also to be considered to include the endpoints of the range, unless expressly stated otherwise. For example, arange of “between 5 and 10,” “from 5 to 10,” or “5-10” should generallybe considered to include the end points 5 and 10.

Further, when the phrase “up to” is used in connection with an amount orquantity, it is to be understood that the amount is at least adetectable amount or quantity. For example, a material present in anamount “up to” a specified amount can be present from a detectableamount and up to and including the specified amount.

The terms “three-dimensional printing system,” “three-dimensionalprinter,” “printing,” and the like generally describe various solidfreeform fabrication techniques for making three-dimensional articles orobjects by stereolithography, selective deposition, jetting, fuseddeposition modeling, multi-jet modeling, and other additivemanufacturing techniques now known in the art or that may be known inthe future that use a build material or ink to fabricatethree-dimensional objects.

I. Inks for 3D Printing

In one aspect, inks for use with a 3D printer are described herein. Insome embodiments, an ink described herein comprises 20-60 wt. %oligomeric curable material; 10-50 wt. % cyclocarbonate (meth)acrylatemonomer; 0.1-5 wt. % photoinitiator; optionally one or more additionalcurable materials differing from the oligomeric curable material and thecyclocarbonate (meth)acrylate monomer; and optionally one or moreadditional component that are non-curable. For instance, in some cases,an ink described herein further comprises at least one colorant, atleast one filler, at least one inhibitor, at least one stabilizingagent, or a combination of two or more of the foregoing. The foregoingweight percents are based on the total weight of the ink. Additionally,as understood by one of ordinary skill in the art, the total amount ofthe oligomeric curable material, cyclocarbonate (meth)acrylate monomer,photoinitiator, additional curable material (if present), and one ormore additional non-curable components (if present) is equal to 100 wt.% for a given ink. Moreover, the photoinitiator is operable to initiatecuring of the oligomeric curable material and/or the cyclocarbonate(meth)acrylate monomer and/or the additional curable material when thephotoinitiator is exposed to incident curing radiation having a peakwavelength λ that is absorbed by the photoinitiator. That is, thephotoinitiator is a photoinitiator of curing of the oligomeric curablematerial and/or the cyclocarbonate (meth)acrylate monomer and/or theadditional curable material.

Notably, inks described herein generally comprise a cyclocarbonate(meth)acrylate monomer. The cyclocarbonate (meth)acrylate monomer hasthe structure of Formula (A1):

wherein R₁ is selected from the group consisting of a linear or branchedC1-C6 alkylene moiety, an alkylene-carbonate moiety, an alkylene-estermoiety, and an alkylene-amide moiety; andwherein R₂ is H or CH₃.

For reference purposes herein, it is to be understood that a “Cn-Cmalkylene moiety” (e.g., a “C1-C6 alkylene moiety”) is a bivalentsaturated aliphatic radical having from “n” to “m” carbon atoms (e.g., 1to 6 carbon atoms, and no more than 6 carbon atoms). In some preferredembodiments, R₁ is a linear or branched C1-C4 alkylene moiety, such asCH₂, which is especially preferred. In some embodiments, analkylene-carbonate moiety is a bivalent radical of the formula.(CH2)_(x)-O—C(O)—O—(CH2)_(y). wherein x and y are integersindependently selected from 1 to 10. Moreover, an alkylene-ester moiety,in some embodiments, is a bivalent radical of the formula.(CH2)_(x)-O—C(O)—O—(CH2)_(y). wherein x and y are integersindependently selected from 1 to 10. Further, an alkylene-amide moiety,in some embodiments, is a bivalent radical of the formula.(CH2)_(x)-O—C(O)—O—(CH2)_(y). wherein x and y are integersindependently selected from 1 to 10.

Additionally, in some preferred embodiments, R₂ is H. In some especiallypreferred embodiments, R₁ is CH₂ and R₂ is H. Thus, in some cases, thecyclocarbonate (meth)acrylate monomer of an ink described herein has thestructure of Formula (A2):

In some embodiments, the cyclocarbonate (meth)acrylate monomer of an inkdescribed herein has a structure selected from (A3) to (A5):

Not intending to be bound by theory, it is believed that the reactivityof the cyclocarbonate (meth)acrylate having the structure of Formula(A2) provides preferred properties during additive manufacturing and inprinted articles. In some embodiments, the cyclocarbonate (meth)acrylatecan participate in crosslinking reactions between polymeric chains. Forexample, the cyclocarbonate (meth)acrylate can polymerize via the vinylmoiety and undergo crosslinking through hydrogen abstraction or otherelectron transfer process.

A cyclocarbonate (meth)acrylate monomer can be present in an inkdescribed herein in any amount not inconsistent with the objectives ofthe present disclosure. In some embodiments, for instance, thecyclocarbonate (meth)acrylate monomer is present in the ink in an amountof 10-50 wt. % or, preferably, in an amount of 15-35 wt. % or 20-30 wt.%, based on the total weight of the ink. Again not intending to be boundby theory, it is believed that the use of such an amount ofcyclocarbonate (meth)acrylate monomer provides improved performance (asdescribed herein), compared to other amounts of cyclocarbonate(meth)acrylate monomer.

As described above, inks according to the present disclosure can offervarious advantages over prior inks, particularly(meth)acrylate-containing inks. For example, inks described herein canbe used to print articles with reduced or improved volumetricpolymerization shrinkage. Inks described herein can also be used toprint articles with improved accuracy and/or precision.

In some embodiments, for instance, an ink described herein, when cured,exhibits a volumetric polymerization shrinkage of no greater than 5%compared to the ink when uncured, wherein the volumetric polymerizationshrinkage is measured according to ASTM D792, the percentage being basedon the uncured ink value as the denominator. In some cases, an inkdescribed herein, when cured, exhibits a volumetric polymerizationshrinkage of no greater than 3% or no greater than 2% compared to theink when uncured when the volumetric polymerization shrinkage ismeasured according to ASTM D792. In some instances, an ink describedherein, when cured, exhibits a volumetric polymerization shrinkage of0.5-5% or 1-3%, compared to the ink when uncured.

Additionally, inks described herein, in some cases, can be used to formarticles having a poly(meth)acrylate network and also having improvedimpact strength and/or tear strength, when compared to other articlesformed from other (meth)acrylate inks not according to the presentinvention. For example, in some embodiments, an ink described herein,when cured, exhibits a notched Izod impact strength of 50 to 200 J/mwhen measured according to ASTM D256 and/or a tear strength of 20 to 200kN/m when measured according to ASTM D624. In some cases, an inkdescribed herein, when cured, exhibits a notched Izod impact strength of50 to 150 J/m, 50 to 100 J/m, or 100 to 200 J/m, when measured accordingto ASTM D256. Moreover, in some embodiments, an ink described herein,when cured, has a tear strength of 20 to 180 kN/m, 20 to 150 kN/m, 20 to100 kN/m, 20 to 60 kN/m, 80 to 200 kN/m, 80 to 180 kN/m, 100 to 150kN/m, or 150 to 200 kN/m, when measured according to ASTM D624.

Not intending to be bound by theory, it is believed that such propertiesas described above can be obtained by using an ink including 20-60 wt. %(or, preferably, 25-50 wt. %) oligomeric curable material, 10-50 wt. %(or, preferably, 15-35 wt. %) cyclocarbonate (meth)acrylate monomer, and0.1-7 wt. % photoinitiator, based on the total weight of the ink. Asdescribed below, it is further to be understood that additionalcomponents (curable or non-curable) can be included in an ink describedherein, and that such additional components can provide certainadditional desired properties to the ink. Thus, as described herein, awide variety of inks for various additive manufacturing applications canbe provided according to the present disclosure, unified by theinventive concepts and technical effects described herein.

Further, inks described herein, in some embodiments, provide one or moreof the foregoing advantages without sacrificing speed of the additivemanufacturing process. Moreover, inks described herein can be used in avariety of different 3D printers or additive manufacturing systems, suchas those based on SLA, DLP, and MJP. The ability to use inks describedherein in SLA and/or DLP is especially to be noted. As discussed furtherherein, an ink described herein, in either the uncured state or thecured state, can have one or more structural properties that provide anadvantage for use of the ink in additive manufacturing, such as additivemanufacturing based on SLA or DLP. For example, in some embodiments, thedynamic viscosity of an uncured ink described herein is greater than 100cP and less than 5000 cP at 25° C., when measured according to ASTMD2983.

Turning now to other specific components of inks described herein, inksdescribed herein may comprise one or more oligomeric curable materialsand, optionally, one or more additional curable materials different fromthe oligomeric curable material and cyclocarbonate (meth)acrylatemonomer of the ink. Such an additional curable material can itself be amonomeric curable material or an oligomeric curable material. In someembodiments, the one or more additional curable materials comprise oneor more species of acrylate monomer and/or oligomer, including but notlimited to acryloyl morpholine, monofunctional acrylates and/orpolyfunctional acrylates. A curable material, for reference purposesherein, comprises a chemical species that includes one or more curableor polymerizable moieties. A “polymerizable moiety,” for referencepurposes herein, comprises a moiety that can be polymerized or cured toprovide a printed 3D article or object. Such polymerizing or curing canbe carried out in any manner not inconsistent with the objectives of thepresent disclosure. In some embodiments, for example, polymerizing orcuring comprises irradiating a polymerizable or curable material withelectromagnetic radiation having sufficient energy to initiate apolymerization or cross-linking reaction. For instance, in some cases,ultraviolet (UV) radiation can be used. Thus, in some instances, apolymerizable moiety comprises a photo-polymerizable or photo-curablemoiety, such as a UV-polymerizable moiety. In some embodiments, acurable material described herein is photo-polymerizable orphoto-curable at wavelengths ranging from about 300 nm to about 400 nmor from about 320 nm to about 380 nm. Alternatively, in other instances,a curable material is photo-polymerizable at visible wavelengths of theelectromagnetic spectrum.

Moreover, a polymerization reaction, in some cases, comprises a freeradical polymerization reaction, such as that between points ofunsaturation, including points of ethyleneic unsaturation. Otherpolymerization reactions may also be used. As understood by one ofordinary skill in the art, a polymerization reaction used to polymerizeor cure a curable material described herein can comprise a reaction of aplurality of “monomers” or chemical species having one or morefunctional groups or moieties that can react with one another to formone or more covalent bonds.

One non-limiting example of a polymerizable moiety of a curable materialdescribed herein is an ethyleneically unsaturated moiety, such as avinyl moiety, allyl moiety, or (meth)acrylate moiety, where the term“(meth)acrylate” throughout this disclosure includes acrylate ormethacrylate or a mixture or combination thereof.

“Oligomeric” species, which are contained in the oligomeric curablematerial described herein, are themselves polymers or oligomers and havea relatively high molecular weight or a relatively high viscosity. Thesespecies are also capable of undergoing additional polymerization, suchas through one or more points of unsaturation described herein. Apopulation of oligomeric species in the oligomeric curable materialdescribed herein can have varying molecular structures and/or formulasthroughout the population (such as may be exhibited, for example, by aspecified mass of a urethane acrylate having a non-unity molecularweight distribution, or by a specified mass of an ethoxylatedpolyethylene glycol having a distribution of ethylene glycol unitsand/or a distribution of ethoxy units within the population). The weightaverage molecular weight of an oligomeric curable material describedherein is generally in the range from about 500 to 6,000. Additionally,in some cases, the oligomeric curable material of an ink describedherein comprises one or more ethylenically unsaturated species having adynamic viscosity of 1,000 to 250,000 cP at 50° C., when measuredaccording to ASTM D2983. In some preferred embodiments, the oligomericcurable material comprises one or more ethylenically unsaturated specieshaving a dynamic viscosity of 1,000 to 200,000 cP at 50° C., whenmeasured according to ASTM D2983. Not intending to be bound by theory,it is believed that such a combination of molecular weight and viscositycontributes to the achievement of the inventive technical effects ofinks described herein.

In contrast to an “oligomeric” species, “monomeric” species, which arecontained in the optional monomeric curable material described herein,are not themselves a polymer or oligomer, and have a relatively lowmolecular weight or a relatively low viscosity. “Monomeric” speciescontained in a monomeric curable material can have a consistent orwell-defined molecular structure and/or formula throughout thepopulation (such as may be exhibited, for instance, by a specified massof ethoxylated (4) bisphenol A diacrylate or a specific mass of theabove-described curable monomer). Additionally, in some embodiments, amonomeric curable material as described herein has a viscosity of 500centipoise (cP) or less at 25° C., when measured according to ASTMD2983, and/or a molecular weight of less than 500, less than 400, orless than 300.

Additionally, an oligomeric curable material and/or a monomeric curablematerial described herein can comprise a monofunctional, difunctional,trifunctional, tetrafunctional, pentafunctional, or higher functionalcurable species. A “monofunctional” curable species, for referencepurposes herein, comprises a chemical species that includes one curableor polymerizable moiety. Similarly, a “difunctional” curable speciescomprises a chemical species that includes two curable or polymerizablemoieties; a “trifunctional” curable species comprises a chemical speciesthat includes three curable or polymerizable moieties; a“tetrafunctional” curable species comprises a chemical species thatincludes four curable or polymerizable moieties; and a “pentafunctional”curable species comprises a chemical species that includes five curableor polymerizable moieties. Thus, in some embodiments, a monofunctionalcurable material of an ink described herein comprises amono(meth)acrylate, a difunctional curable material of an ink describedherein comprises a di(meth)acrylate, a trifunctional curable material ofan ink described herein comprises a tri(meth)acrylate, a tetrafunctionalcurable material of an ink described herein comprises atetra(meth)acrylate, and a pentafunctional curable material of an inkdescribed herein comprises a penta(meth)acrylate. Other monofunctional,difunctional, trifunctional, tetrafunctional, and pentafunctionalcurable materials may also be used.

Moreover, a monofunctional, difunctional, trifunctional,tetrafunctional, and pentafunctional curable material, in some cases,can comprise a relatively low molecular weight species, i.e., amonomeric species, or a relatively high molecular weight species, i.e.,an oligomeric species.

In general, any oligomeric curable material or combination of oligomericcurable materials not inconsistent with the objectives of the presentdisclosure may be used in an ink described herein. In some cases, anoligomeric curable material comprises a polyester (meth)acrylateoligomer, a urethane (meth)acrylate oligomer, or an epoxy(meth)acrylateoligomer. Urethane (meth)acrylates are especially preferred in somecases. Further, in some embodiments, an oligomeric curable materialdescribed herein comprises an aliphatic polyester urethane acrylateoligomer and/or an acrylate amine oligomeric resin, such as EBECRYL7100. In some cases, an oligomeric curable material described hereincomprises a polypropylene glycol mono(meth)acrylate or polyethyleneglycol mono(meth)acrylate. In some embodiments, an oligomeric curablematerial comprises a monofunctional aliphatic urethane (meth)acrylate.Moreover, in some cases, an oligomeric curable material comprises adiacrylate and/or dimethacrylate ester of an aliphatic, cycloaliphaticor aromatic diol, including polyethylene glycol, ethoxylated orpropoxylated neopentyl glycol, ethoxylated or propoxylated bisphenol A,ethoxylated or propoxylated bisphenol F, ethoxylated or propoxylatedbisphenol S, ethoxylated or propoxylated1,1,1-trimethylolpropanetri(meth)acrylate, or ethoxylated orpropoxylated glycerol tri(meth)acrylate. An oligomeric material may alsocomprise a cycloaliphatic epoxy.

Some non-limiting examples of commercially available oligomeric curablematerials useful in some embodiments described herein include thefollowing: alkoxylated tetrahydrofurfuryl acrylate, commerciallyavailable from SARTOMER under the trade name SR 611; monofunctionalurethane acrylate, commercially available from RAHN USA under the tradename GENOMER 1122; an aliphatic urethane diacrylate, commerciallyavailable from ALLNEX under the trade name EBECRYL 8402; amultifunctional acrylate oligomer, commercially available from DYMAXCorporation under the trade name BR-952; and aliphatic polyetherurethane acrylate, commercially available from DYMAX Corporation underthe trade name BR-371S. Other commercially available oligomeric curablematerials may also be used.

Urethane (meth)acrylates suitable for use in inks described herein, insome cases, can be prepared in a known manner, typically by reacting ahydroxyl-terminated urethane with acrylic acid or methacrylic acid togive the corresponding urethane (meth)acrylate, or by reacting anisocyanate-terminated prepolymer with hydroxyalkyl acrylates ormethacrylates to give the urethane (meth)acrylate. Suitable processesare disclosed, inter alia, in EP-A 114 982 and EP-A 133 908. The weightaverage molecular weight of such (meth)acrylate oligomers, in somecases, can be from about 500 to 6,000. Urethane (meth)acrylates are alsocommercially available from SARTOMER under the product names CN980,CN981, CN975 and CN2901, or from BOMAR Specialties Co. under the productname BR-741, BR-771 F, BR 7432GB and BR751 MB.

The oligomeric curable material can be present in an ink describedherein in any amount not inconsistent with the objectives of the presentdisclosure. In some cases, the oligomeric curable material, in total, ispresent in the ink in an amount of 20-60 wt. % or, preferably, 25-50 wt.%, based on the total weight of the ink.

In addition, any monomeric curable material or combination of monomericcurable materials not inconsistent with the objectives of the presentdisclosure may be used as an additional monomeric curable materialcomponent. In some cases, a monomeric curable material of an inkdescribed herein comprises one or more species of (meth)acrylates, suchas one or more monofunctional, difunctional, trifunctional,tetrafunctional (meth)acrylates, and/or pentafunctional (meth)acrylates.In some embodiments, for instance, a monomeric curable materialcomprises methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl(meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl(meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate,n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, 2-hydroxyethyl(meth)acrylate, 2- or 3-hydroxypropyl (meth)acrylate, 2-methoxyethyl(meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2- or 3-ethoxypropyl(meth)acrylate, tetrahydrofurfuryl methacrylate, isobornyl(meth)acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, cyclohexylmethacrylate, 2-phenoxyethyl acrylate, glycidyl acrylate, isodecylacrylate, 2-phenoxyethyl (meth)acrylate, lauryl methacrylate, or acombination thereof. In some embodiments, a monomeric curable materialcomprises one or more of allyl acrylate, allyl methacrylate, triethyleneglycol di(meth)acrylate, tricyclodecane dimethanol diacrylate, andcyclohexane dimethanol diacrylate. Additionally, in some cases, amonomeric curable material comprises diacrylate and/or dimethacrylateesters of aliphatic, cycloaliphatic or aromatic diols, including 1,3- or1,4-butanediol, neopentyl glycol, 1,6-hexanediol, diethylene glycol,triethylene glycol, tetraethylene glycol, tripropylene glycol,1,4-dihydroxymethylcyclohexane, 2,2-bis(4-hydroxycyclohexyl)propane orbis(4-hydroxycyclohexyl)methane, hydroquinone, 4,4′-dihydroxybiphenyl,bisphenol A, bisphenol F, or bisphenol S. A monomeric curable materialdescribed herein may also comprise 1,1-trimethylolpropanetri(meth)acrylate, pentaerythritol monohydroxy tri(meth)acrylate,dipentaerythritol monohydroxy penta(meth)acrylate, and/orbis(trimethylolpropane) tetra(meth)acrylate. Further, in some cases, amonomeric curable material can comprise an ethoxylated or propoxylatedspecies, such as ethoxylated or propoxylated neopentyl glycol,ethoxylated or propoxylated bisphenol A, ethoxylated or propoxylatedbisphenol F, ethoxylated or propoxylated bisphenol S, ethoxylated orpropoxylated 1,1,1-trimethylolpropanetri(meth)acrylate, or ethoxylatedor propoxylated glycerol tri(meth)acrylate. In some cases, a monomericcurable material comprises a cycloaliphatic epoxy.

Additional non-limiting examples of commercially available monomericcurable materials useful in some embodiments described herein includethe following: isobornyl acrylate (IBOA), commercially available fromSARTOMER under the trade name SR 506; isobornyl methacrylate,commercially available from SARTOMER under the trade name SR 423A;triethylene glycol diacrylate, commercially available from SARTOMERunder the trade name SR 272; triethylene glycol dimethacrylate,commercially available from SARTOMER under the trade name SR 205;tricyclodecane dimethanol diacrylate, commercially available fromSARTOMER under the trade name SR 833S; tris(2-hydroxy ethyl)isocyanuratetriacrylate, commercially available from SARTOMER under the trade nameSR 368; 2-phenoxyethyl acrylate, commercially available from SARTOMERunder the trade name SR 339; ethyoxylated (3 mole) bisphenol Adiacrylate, commercially available from SARTOMER under the trade name SR349; a cyclic monofunctional acrylate, commercially available by RAHNUSA Corp. under the trade name GENOMER 1120; and dipentaerythritolpentaacrylate, commercially available from SARTOMER under the trade nameSR 399 LV. Other commercially available monomeric curable materials mayalso be used.

An additional monomeric curable material, when used, can be present inan ink described herein in any amount not inconsistent with theobjectives of the present disclosure. In some cases, the additionalmonomeric curable material, in total, is present in an amount up toabout 40 wt. %, up to about 30 wt. %, up to about 25 wt. %, or up toabout 20 wt. %, based on the total weight of the ink. In some cases, anink described herein comprises about 0-40 wt. %, 10-40 wt. %, or 15-35wt. % additional monomeric curable material, based on the total weightof the ink. In some instances, an ink described herein does not includeany additional monomeric curable material other than the cyclocarbonate(meth)acrylate monomer.

Inks described herein also comprise one or more photoinitiators. Anyphotoinitiator not inconsistent with the objectives of the presentdisclosure may be used in an ink described herein. In some embodiments,for example, the photoinitiator comprises an alpha-cleavage type(unimolecular decomposition process) photoinitiator or a hydrogenabstraction photosensitizer-tertiary amine synergist, operable to absorblight between about 250 nm and about 400 nm or between about 300 nm andabout 385 nm, to yield free radical(s). Examples of alpha cleavagephotoinitiators are Irgacure 184 (CAS 947-19-3), Irgacure 369 (CAS119313-12-1), and Irgacure 819 (CAS 162881-26-7). An example of aphotosensitizer-amine combination is Darocur BP (CAS 119-61-9) withdiethylaminoethylmethacrylate.

In addition, in some instances, photoinitiators comprise benzoins,including benzoin, benzoin ethers, such as benzoin methyl ether, benzoinethyl ether and benzoin isopropyl ether, benzoin phenyl ether andbenzoin acetate, acetophenones, including acetophenone,2,2-dimethoxyacetophenone and 1,1-dichloroacetophenone, benzil, benzilketals, such as benzil dimethyl ketal and benzil diethyl ketal,anthraquinones, including 2-methylanthraquinone, 2-ethylanthraquinone,2-tert-butylanthraquinone, 1-chloroanthraquinone and2-amylanthraquinone, triphenylphosphine, benzoylphosphine oxides, suchas 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Lucirin TPO),benzophenones, such as benzophenone and4,4′-bis(N,N′-dimethylamino)benzophenone, thioxanthones and xanthones,acridine derivatives, phenazine derivatives, quinoxaline derivatives or1-phenyl-1,2-propanedione, 2-O-benzoyl oxime, 1-aminophenyl ketones or1-hydroxyphenyl ketones, such as 1-hydroxycyclohexyl phenyl ketone,phenyl 1-hydroxyisopropyl ketone and 4-isopropylphenyl1-hydroxyisopropyl ketone.

Photoinitiators can also comprise photoinitiators operable for use witha HeCd laser radiation source, including acetophenones,2,2-dialkoxybenzophenones and 1-hydroxyphenyl ketones, such as1-hydroxycyclohexyl phenyl ketone or 2-hydroxyisopropyl phenyl ketone(=2-hydroxy-2,2-dimethylacetophenone). Additionally, in some cases,photoinitiators comprise photoinitiators operable for use with an Arlaser radiation source including benzil ketals, such as benzil dimethylketal. In some embodiments, a suitable photoinitiator comprises anα-hydroxyphenyl ketone, benzil dimethyl ketal or2,4,6-trimethylbenzoyldiphenylphosphine oxide or a mixture thereof.

Another class of photoinitiators that may be included in an inkdescribed herein comprises ionic dye-counter ion compounds capable ofabsorbing actinic radiation and generating free radicals forpolymerization initiation. Some ionic dye-counter ion compounds andtheir mode of operation are disclosed in EP-A-0 223 587 and U.S. Pat.Nos. 4,751,102; 4,772,530; and 4,772,541. A photoinitiator describedherein may also be a cationic photoinitiator such as a triphenylsulphonium photoinitiator.

A photoinitiator can be present in an ink described herein in any amountnot inconsistent with the objectives of the present disclosure. In someembodiments, a photoinitiator is present in an ink in an amount of up toabout 5 wt. %, up to about 4 wt. %, or up to about 3 wt. %, based on thetotal weight of the ink. In some cases, a photoinitiator is present inan amount of about 0.1-5 wt. %, 0.1-4 wt. %, 0.1-3.5 wt. %, 0.1-2 wt. %,0.5-5 wt. %, 0.5-4 wt. %, 0.5-3.5 wt. %, 1-5 wt. %, 1-4 wt. %, 1-3.5 wt.%, 2-5 wt. %, or 2-4 wt. %.

It is further to be understood that the amounts (weight percents)described in the immediately preceding paragraph refer tophotoinitiators that are non-oligomeric and non-polymeric. That is, theamounts described above refer to “monomeric” or “molecular”photoinitiators, which may, for instance, have a molecular weight ofless than 400. However, it is also to be understood that oligomeric orpolymeric photoinitiators may be used in inks and methods describedherein. But in such an instance (when an oligomeric or polymericphotoinitiator is used), then the amounts (weight percents) above are tobe calculated without taking into account the weight of the oligomericor polymeric portion or moiety of the oligomeric or polymericphotoinitiator. In other words, to determine the overall amount (weightpercent) of the oligomeric or polymeric photoinitiator that is presentin the ink, the calculation (specifically, the numerator) should bebased on only the molecular weight of the photoactive moiety of thephotoinitiator, not on the molecular weight(s) of the remaining moietiesor repeating units of the oligomeric or polymeric photoinitiator (forpurposes of the present disclosure).

Turning to possible additional components of inks described herein, inksdescribed herein can further comprise one or more photosensitizers. Ingeneral, such a sensitizer can be added to an ink to increase theeffectiveness of one or more photoinitiators that may also be present.In some cases, a sensitizer comprises isopropylthioxanthone (ITX) or2-chlorothioxanthone (CTX).

A sensitizer can be present in an ink in any amount not inconsistentwith the objectives of the present disclosure. In some embodiments, asensitizer is present in an amount ranging from about 0.1 wt. % to about2 wt. % or from about 0.5 wt. % to about 1 wt. %, based on the totalweight of the ink. However, in other cases, an ink described hereinexcludes a sensitizer such as described above.

Turning to another possible component of the ink described herein, inksdescribed herein can also comprise at least one colorant. Such acolorant of an ink described herein can be a particulate colorant, suchas a particulate pigment, or a molecular colorant, such as a moleculardye. Any such particulate or molecular colorant not inconsistent withthe objectives of the present disclosure may be used. In some cases, forinstance, the colorant of an ink comprises an inorganic pigment, such asTiO₂ and/or ZnO. In some embodiments, the colorant of an ink comprises acolorant for use in a RGB, sRGB, CMY, CMYK, L*a*b*, or Pantone®colorization scheme. Moreover, in some cases, a particulate colorantdescribed herein has an average particle size of less than about 5 μm ,or less than about 1 μm. In some instances, a particulate colorantdescribed herein has an average particle size of less than about 500 nm,such as an average particle size of less than about 400 nm, less thanabout 300 nm, less than about 250 nm, less than about 200 nm, or lessthan about 150 nm. In some instances, a particulate colorant has anaverage particle size of about 50-5000 nm, about 50-1000 nm, or about50-500 nm.

A colorant can be present in an ink described herein in any amount notinconsistent with the objectives of the present disclosure. In somecases, colorant is present in the ink in an amount up to about 2 wt. %,or an amount of about 0.005-2 wt. %, 0.01-2 wt. %, 0.01-1.5 wt. %,0.01-1 wt. %, 0.01-0.5 wt. %, 0.1-2 wt. %, 0.1-1 wt. %, 0.1-0.5 wt. %,or 0.5-1.5 wt. %, based on the total weight of the ink.

Moreover, inks described herein, in some embodiments, further compriseone or more polymerization inhibitors and/or stabilizing agents. Apolymerization inhibitor can be added to an ink to provide additionalthermal stability to the composition. Any polymerization inhibitor notinconsistent with the objectives of the present disclosure may be used.Moreover, a polymerization inhibitor can retard or decrease the rate ofpolymerization, and/or prevent polymerization from occurring for someperiod of time or “induction time” until the polymerization inhibitor isconsumed. Further, in some cases, a polymerization inhibitor describedherein is an “addition type” inhibitor. An inhibitor described hereincan also be a “chain transfer type” inhibitor. In some instances, asuitable polymerization inhibitor comprises methoxyhydroquinone (MEHQ).

A stabilizing agent, in some embodiments, comprises one or moreanti-oxidants. A stabilizing agent can comprise any anti-oxidant notinconsistent with the objectives of the present disclosure. In somecases, suitable anti-oxidants include various aryl compounds, includingbutylated hydroxytoluene (BHT), which can also be used as apolymerization inhibitor in some embodiments described herein. Moregenerally, a single species may serve as both a stabilizing agent and apolymerization inhibitor. It is also possible, in some cases, to use aplurality of inhibitors and/or stabilizing agents, wherein differinginhibitors and/or stabilizers provide differing effects and/or worksynergistically.

A polymerization inhibitor and/or a stabilizing agent can be present inan ink in any amount not inconsistent with the objectives of the presentdisclosure. In some embodiments, a polymerization inhibitor is presentin an amount ranging from about 0.01 wt. % to about 2 wt. % or fromabout 0.05 wt. % to about 1 wt. %. Similarly, in some cases, astabilizing agent is present in an ink in an amount ranging from about0.1 wt. % to about 5 wt. %, from about 0.5 wt. % to about 4 wt. %, orfrom about 1 wt. % to about 3 wt. %, based on the total weight of theink.

In some embodiments, an ink described herein may contain viscositymodifying agents. Non-limiting examples of viscosity modifying agentsinclude a saturated fatty acid or a combination of saturated fattyacids, or an oil, such as a plant oil. The inks described herein maycomprise up to 5 wt. % up to 3 wt. %, up to 1 wt. %, up to 0.5 wt. %, orup to 0.1 wt. % of a viscosity modifying agent not inconsistent with theobjectives of the present disclosure.

An ink described herein may also include other so-called fillers. Such afiller, in general, can be non-curable, such that the filler does notparticipate chemically as a reactant in a polymerization used to form apolymer network during additive manufacturing. Such a filler can also beused to impart one or more desirable properties to the ink (such ascolor, mechanical strength, or electrical conductivity). Non-limitingexamples of fillers include some of the possible additional componentsmentioned above (such as colorants) as well as inorganic fillers such asceramic, metal, or other particles and/or organic fillers such asdiscrete polymer particles.

Inks described herein can exhibit a variety of desirable properties.Some desirable properties of inks have already been described above(e.g., low volumetric shrinkage). An ink can also exhibit otherdesirable properties. For example, an ink described herein can have anyfreezing point, melting point, and/or other phase transition temperaturenot inconsistent with the objectives of the present disclosure. In somecases, an ink has freezing and melting points consistent withtemperatures used in some 3D printing systems, including 3D printingsystems designed for use with phase changing inks. In some embodiments,the freezing point of an ink is greater than about 40° C. In someinstances, for example, an ink has a freezing point centered at atemperature ranging from about 45° C. to about 55° C. or from about 50°C. to about 80° C. In some cases, an ink has a freezing point belowabout 40° C. or below about 30° C.

Further, in some embodiments described herein, an ink exhibits a sharpfreezing point or other phase transition. In some cases, for instance,an ink freezes over a narrow range of temperatures, such as a range ofabout 1-10° C., about 1-8° C., or about 1-5° C. In some embodiments, anink having a sharp freezing point freezes over a temperature range ofX±2.5° C., where X is the temperature at which the freezing point iscentered (e.g., X=65° C.).

In addition, an ink described herein, in some cases, is fluid at jettingtemperatures encountered in some 3D printing systems. Moreover, in someembodiments, an ink solidifies once deposited on a surface during thefabrication of a three-dimensionally printed article or object.Alternatively, in other instances, an ink remains substantially fluidupon deposition on a surface. Solidification of an ink, in someembodiments, occurs through a phase change of the ink or a component ofthe ink. The phase change can comprise a liquid to solid phase change ora liquid to semi-solid phase change. Further, in some instances,solidification of an ink comprises an increase in viscosity of the ink,such as an increase in viscosity from a low viscosity state to a highviscosity state. Solidification of an ink can also occur due to curingof the ink.

Additionally, in some embodiments, the inks described herein, whennon-cured, have a viscosity profile consistent with the requirements andparameters of one or more 3D printing systems, such as an MP or SLAsystem. For example, in some cases, an ink described herein has adynamic viscosity at 30° C. of 1600 centipoise (cP) or less, 1200 cP orless, or 800 cP or less. In a preferred embodiment, an ink describedherein has a dynamic viscosity of 500 cP or less at 30° C., whenmeasured according to ASTM standard D2983 (e.g., using a BrookfieldModel DV-II+ Viscometer). In some cases, an ink described herein whennon-cured exhibits a dynamic viscosity of about 200-1600 cP, about200-1200 cP, about 200-800 cP, about 200-500 cP, or about 200-400 cP at30° C., when measured according to ASTM D2983. In other preferredembodiments, an ink described herein, when uncured, has a dynamicviscosity greater than 500 cP and less than 2500 cP at 50° C., whenmeasured according to ASTM D2983.

Inks described herein can also exhibit a variety of desirableproperties, in addition to those described hereinabove, in a curedstate. An ink in a “cured” state, as used throughout the presentdisclosure, comprises an ink that includes a curable material orpolymerizable component that has been at least partially cured, i.e., atleast partially polymerized and/or cross-linked. For instance, in somecases, a cured ink is at least about 70% polymerized or cross-linked orat least about 80% polymerized or cross-linked. In some embodiments, acured ink is at least about 85%, at least about 90%, at least about 95%,at least about 98%, or at least 99% polymerized or cross-linked. In someinstances, a cured ink is between about 80% and about 99% polymerized orcross-linked.

In some cases, for example, an ink described herein, when cured, has animpact resistance (notched) as described above. Moreover, in some cases,an ink described herein, when cured, can exhibit a plurality of theproperties described in the present disclosure.

Inks described herein can be produced in any manner not inconsistentwith the objectives of the present disclosure. In some embodiments, forinstance, a method for the preparation of an ink described hereincomprises the steps of mixing the components of the ink, melting themixture, and filtering the molten mixture. Melting the mixture, in somecases, is carried out at a temperature of about 75° C. or in a rangefrom about 75° C. to about 85° C. In some embodiments, an ink describedherein is produced by placing all components of the ink in a reactionvessel and heating the resulting mixture to a temperature ranging fromabout 75° C. to about 85° C. with stirring. The heating and stirring arecontinued until the mixture attains a substantially homogenized moltenstate. In general, the molten mixture can be filtered while in aflowable state to remove any large undesirable particles that mayinterfere with jetting or extrusion or other printing process. Thefiltered mixture can then be cooled to ambient temperatures and storeduntil ready for use in a 3D printing system.

II. Methods of Forming a 3D Article

In another aspect, methods of forming or “printing” a 3D article orobject by additive manufacturing are described herein. Methods offorming a 3D article or object described herein can include forming the3D article from a plurality of layers of an ink described herein in alayer-by-layer manner (such as in MJP or SLA printing methods). Forexample, in some instances, an MP method of printing a 3D articlecomprises selectively depositing layers of an ink described herein in afluid state onto a substrate, such as a build pad of a 3D printingsystem. The method can further comprise further curing (e.g.,photocuring) the ink. Moreover, curing can comprise polymerizing one ormore polymerizable moieties or functional groups of one or morecomponents of the ink. In some cases, a layer of deposited ink is curedprior to the deposition of another or adjacent layer of ink.Additionally, curing one or more layers of deposited ink, in someembodiments, is carried out by exposing the one or more layers toelectromagnetic radiation, such as UV light, visible light, or infraredlight, as described above. In addition, in some embodiments, such amethod further comprises supporting at least one of the layers of theink with a support material, before or after curing. Any supportmaterial not inconsistent with the objectives of the present disclosuremay be used, as described further below.

Alternatively, a method of printing a 3D article comprises retaining anink in a fluid state in a container; selectively applying energy to theink in the container to solidify at least a portion of a first fluidlayer of the ink, thereby forming a first solidified layer that definesa first cross-section of the article; raising or lowering the firstsolidified layer to provide a second fluid layer of the ink at a surfaceof the fluid ink in the container; and selectively applying energy tothe ink in the container to solidify at least a portion of the secondfluid layer of the ink, thereby forming a second solidified layer thatdefines a second cross-section of the article, the first cross-sectionand the second cross-section being bonded to one another in az-direction. Moreover, in some such embodiments, selectively applyingenergy to the ink in the container comprises photocuring the ink.Further, such a method can be carried out a relatively high printingspeed, even for the formation of a relatively large 3D article. Forexample, in some cases, a method of printing described herein has aprint speed of 20-60 mm/hr, such as 50 mm/hr.

Further, in some embodiments of methods described herein, one or morelayers of an ink described herein has a thickness of about 10 μm toabout 100 μm , about 10 μm to about 80 μm , about 10 μm to about 50 μm ,about 20 μm to about 100 μm , about 20 μm to about 80 μm , or about 20μm to about 40 μm. Other thicknesses are also possible.

Methods of forming a 3D article by additive manufacturing can alsoinclude forming the object in a manner other than a layer-by-layermanner.

Additionally, any ink described hereinabove in Section I may be used ina method described herein. For example, in some cases, a methoddescribed herein comprises 20-60 wt. % oligomeric curable material;10-50 wt. % cyclocarbonate (meth)acrylate monomer; 0.1-5 wt. %photoinitiator; optionally up to 40 wt. % one or more additional curablematerials differing from the oligomeric curable material and thecyclocarbonate (meth)acrylate monomer; and optionally up to 10 wt. % oneor more additional component that are non-curable, wherein the weightpercentages are based on the total weight of the ink, and wherein thetotal amount of all of the foregoing components combined is 100 wt. %.

Further details regarding various methods, including “materialdeposition” methods (such as MJP) or “vat polymerization” methods (suchas SLA), are provided below.

A. Material Deposition Methods

In a material deposition method, one or more layers of an ink describedherein are selectively deposited onto a substrate and cured. Curing ofthe ink may occur after selective deposition of one layer, each layer,several layers, or all layers of the ink.

In some instances, an ink described herein is selectively deposited in afluid state onto a substrate, such as a build pad of a 3D printingsystem. Selective deposition may include, for example, depositing theink according to preselected CAD parameters. For example, in someembodiments, a CAD file drawing corresponding to a desired 3D article tobe printed is generated and sliced into a sufficient number ofhorizontal slices. Then, the ink is selectively deposited, layer bylayer, according to the horizontal slices of the CAD file drawing toprint the desired 3D article. A “sufficient” number of horizontal slicesis the number necessary for successful printing of the desired 3Darticle, e.g., to produce it accurately and precisely.

Further, in some embodiments, a preselected amount of ink describedherein is heated to the appropriate temperature and jetted through aprint head or a plurality of print heads of a suitable inkjet printer toform a layer on a print pad in a print chamber. In some cases, eachlayer of ink is deposited according to preselected CAD parameters. Asuitable print head to deposit the ink, in some embodiments, is apiezoelectric print head. Additional suitable print heads for thedeposition of ink and support material described herein are commerciallyavailable from a variety of ink jet printing apparatus manufacturers.For example, Xerox, Hewlett Packard, or Ricoh print heads may be used insome instances.

Additionally, in some embodiments, an ink described herein remainssubstantially fluid upon deposition. Alternatively, in other instances,the ink exhibits a phase change upon deposition and/or solidifies upondeposition. Moreover, in some cases, the temperature of the printingenvironment can be controlled so that the jetted droplets of inksolidify on contact with the receiving surface. In other embodiments,the jetted droplets of ink do not solidify on contact with the receivingsurface, remaining in a substantially fluid state. Additionally, in someinstances, after each layer is deposited, the deposited material isplanarized and cured with electromagnetic (e.g., UV, visible, orinfrared light) radiation prior to the deposition of the next layer.Optionally, several layers can be deposited before planarization andcuring, or multiple layers can be deposited and cured followed by one ormore layers being deposited and then planarized without curing.Planarization corrects the thickness of one or more layers prior tocuring the material by evening the dispensed material to remove excessmaterial and create a uniformly smooth exposed or flat up-facing surfaceon the support platform of the printer. In some embodiments,planarization is accomplished with a wiper device, such as a roller,which may be counter-rotating in one or more printing directions but notcounter-rotating in one or more other printing directions. In somecases, the wiper device comprises a roller and a wiper that removesexcess material from the roller. Further, in some instances, the wiperdevice is heated. It should be noted that the consistency of the jettedink described herein prior to curing, in some embodiments, shoulddesirably be sufficient to retain its shape and not be subject toexcessive viscous drag from the planarizer.

Moreover, a support material, when used, can be deposited in a mannerconsistent with that described hereinabove for the ink. The supportmaterial, for example, can be deposited according to the preselected CADparameters such that the support material is adjacent or continuous withone or more layers of the ink. Jetted droplets of the support material,in some embodiments, solidify or freeze on contact with the receivingsurface. In some cases, the deposited support material is also subjectedto planarization, curing, or planarization and curing. Any supportmaterial not inconsistent with the objectives of the present disclosuremay be used.

Layered deposition of the ink and support material can be repeated untilthe 3D article has been formed. In some embodiments, a method ofprinting a 3D article further comprises removing the support materialfrom the ink.

Curing of the ink may occur after selective deposition of one layer ofink, of each layer of ink, of several layers of ink, or of all layers ofthe ink necessary to print the desired 3D article. In some embodiments,a partial curing of the deposited ink is performed after selectivedeposition of one layer of ink, each layer of ink, several layers ofink, or all layers of the ink necessary to print the desired 3D article.A “partially cured” ink, for reference purposes herein, is one that canundergo further curing. For example, a partially cured ink is up toabout 30% polymerized or cross-linked or up to about 50% polymerized orcross-linked. In some embodiments, a partially cured ink is up to about60%, up to about 70%, up to about 80%, up to about 90%, or up to about95% polymerized or cross-linked.

Partial curing of the deposited ink can include irradiating the ink withan electromagnetic radiation source or photocuring the ink (includingwith curing radiation described hereinabove). Any electromagneticradiation source not inconsistent with the objectives of the presentdisclosure may be used, e.g., an electromagnetic radiation source thatemits UV, visible or infrared light. For example, in some embodiments,the electromagnetic radiation source can be one that emits light havinga wavelength from about 300 nm to about 900 nm, e.g., a Xe arc lamp.

Further, in some embodiments, a post-curing is performed after partiallycuring is performed. For example, in some cases, post-curing is carriedout after selectively depositing all layers of the ink necessary to forma desired 3D article, after partially curing all layers of the ink, orafter both of the foregoing steps have been performed. Moreover, in someembodiments, post-curing comprises photocuring. Again, anyelectromagnetic radiation source not inconsistent with the objectives ofthe present disclosure may be used for a post-curing step describedherein. For example, in some embodiments, the electromagnetic radiationsource can be a light source that has a higher energy, a lower energy,or the same energy as the electromagnetic radiation source used forpartial curing. In some cases wherein the electromagnetic radiationsource used for post-curing has a higher energy (i.e., a shorterwavelength) than that used for partial curing, a Xe arc lamp can be usedfor partial curing and a Hg lamp can be used for post-curing.

Additionally, after post-curing, in some cases, the deposited layers ofink are at least about 80% polymerized or cross-linked or at least about85% polymerized or cross-linked. In some embodiments, the depositedlayers of ink are at least about 90%, at least about 95%, at least about98%, or at least about 99% polymerized or cross-linked. In someinstances, the deposited layers of ink are about 80-100%, about 80-99%,about 80-95%, about 85-100%, about 85-99%, about 85-95%, about 90-100%,or about 90-99% polymerized or cross-linked.

B. Vat Polymerization Methods

It is also possible to form a 3D article from an ink described hereinusing a vat polymerization method, such as an SLA method. Thus, in somecases, a method of printing a 3D article described herein comprisesretaining an ink described herein in a fluid state in a container andselectively applying energy (particularly, for instance, curingradiation) to the ink in the container to solidify at least a portion ofa fluid layer of the ink, thereby forming a solidified layer thatdefines a cross-section of the 3D article. Additionally, a methoddescribed herein can further comprise raising or lowering the solidifiedlayer of ink to provide a new or second fluid layer of unsolidified inkat the surface of the fluid ink in the container, followed by againselectively applying energy (e.g., the curing radiation) to the ink inthe container to solidify at least a portion of the new or second fluidlayer of the ink to form a second solidified layer that defines a secondcross-section of the 3D article. Further, the first and secondcross-sections of the 3D article can be bonded or adhered to one anotherin the z-direction (or build direction corresponding to the direction ofraising or lowering recited above) by the application of the energy forsolidifying the ink. Moreover, in some instances, the electromagneticradiation has an average wavelength of 300-900 nm, and in otherembodiments the electromagnetic radiation has an average wavelength thatis less than 300 nm. In some cases, the curing radiation is provided bya computer controlled laser beam. In addition, in some cases, raising orlowering a solidified layer of ink is carried out using an elevatorplatform disposed in the container of fluid ink. A method describedherein can also comprise planarizing a new layer of fluid ink providedby raising or lowering an elevator platform. Such planarization can becarried out, in some cases, by a wiper or roller.

It is further to be understood that the foregoing process can berepeated a desired number of times to provide the 3D article. Forexample, in some cases, this process can be repeated “n” number oftimes, wherein n can be up to about 100,000, up to about 50,000, up toabout 10,000, up to about 5000, up to about 1000, or up to about 500.Thus, in some embodiments, a method of printing a 3D article describedherein can comprise selectively applying energy (e.g., curing radiation)to an ink in a container to solidify at least a portion of an nth fluidlayer of the ink, thereby forming an nth solidified layer that definesan nth cross-section of the 3D article, raising or lowering the nthsolidified layer of ink to provide an (n+1)th layer of unsolidified inkat the surface of the fluid ink in the container, selectively applyingenergy to the (n+1)th layer of ink in the container to solidify at leasta portion of the (n+1)th layer of the ink to form an (n+1)th solidifiedlayer that defines an (n+1)th cross-section of the 3D article, raisingor lowering the (n+1)th solidified layer of ink to provide an (n+2)thlayer of unsolidified ink at the surface of the fluid ink in thecontainer, and continuing to repeat the foregoing steps to form the 3Darticle. Further, it is to be understood that one or more steps of amethod described herein, such as a step of selectively applying energy(e.g., curing radiation) to a layer of ink, can be carried out accordingto an image of the 3D article in a computer-readable format. Generalmethods of 3D printing using stereolithography are further described,inter alia, in U.S. Pat. Nos. 5,904,889 and 6,558,606.

Performing a printing process described above can provide a printed 3Darticle from an ink described herein that has a high feature resolution.The “feature resolution” of an article, for reference purposes herein,can be the smallest controllable physical feature size of the article.The feature resolution of an article can be described in terms of a unitof distance such as microns (μm ), or in terms of dots per inch (dpi).As understood by one of ordinary skill in the art, a higher featureresolution corresponds to a higher dpi value but a lower distance valuein μm. In some cases, an article formed by depositing or solidifying anink described herein can have a feature resolution of about 500 μm orless, about 200 μm or less, about 100 μm or less, or about 50 μm orless, including at elevated temperatures. In some embodiments, anarticle has a feature resolution between about 50 μm and about 500 μm,between about 50 μm and about 200 μm, between about 50 μm and about 100μm, or between about 100 μm and about 200 μm. Correspondingly, in someinstances, an article described herein has a feature resolution of atleast about 100 dpi, at least about 200 dpi, at least about 250 dpi, atleast about 400 dpi, or at least about 500 dpi. In some cases, thefeature resolution of an article is between about 100 dpi and about 600dpi, between about 100 dpi and about 250 dpi, or between about 200 dpiand about 600 dpi.

In a vat polymerization method such as described above, the ink may bepartially cured as described in Section IIA above. For example, in someembodiments, selectively applying energy to the ink in the container tosolidify at least a portion of a fluid layer of the ink may includepartially curing at least a portion of a fluid layer of the ink. Inother embodiments, partial curing of at least a portion of a fluid layerof the ink may occur after a first layer of the ink is provided andsolidified, before or after a second layer of the ink is provided orsolidified, or before or after one, several, or all subsequent layers ofthe ink are provided or solidified.

Additionally, in some embodiments of a vat polymerization methoddescribed herein, after partial curing or after the desired 3D articleis formed, post-curing as described in Section IIA above may beperformed. The desired 3D article may be, for example, an article thatcorresponds to the design in a CAD file.

III. Printed 3D Articles

In another aspect, printed 3D articles are described herein. In someembodiments, a printed 3D article is formed from an ink describedherein. Any ink described hereinabove in Section I may be used. Forexample, in some cases, the ink comprises 20-60 wt. % oligomeric curablematerial; 10-40 wt. % cyclocarbonate (meth)acrylate monomer; 0.1-5 wt. %photoinitiator; optionally up to 40 wt. % one or more additional curablematerials differing from the oligomeric curable material and thecyclocarbonate (meth)acrylate monomer; and optionally up to 10 wt. % oneor more additional component that are non-curable, wherein the weightpercentages are based on the total weight of the ink, and wherein thetotal amount of all of the foregoing components combined is 100 wt. %.Further, in some cases, a printed 3D article described herein is formedprimarily from a poly(meth)acrylate polymer network.

Some embodiments of inks for 3D printing are also further illustrated inthe following non-limiting Examples.

EXAMPLE 1 Method of Preparing Inks

Inks according to some embodiments described herein were prepared asfollows. Specifically, to prepare various inks, the components in thefollowing Tables I-IV were mixed in a reaction vessel to form specificinks, as identified in the Tables. The amounts of various components inTables I-IV refer to the wt. % of each component of the identified ink,based on the total weight of the ink. For each ink, the appropriatemixture was heated to a temperature of about 75-85° C. with stirring.The heating and stirring were continued until the mixture attained asubstantially homogenized molten state. The molten mixture was thenfiltered. Next, the filtered mixture was allowed to cool to ambienttemperature. Values of some measured properties are also provided in theTables below. The units for measured values are as follows. Forvolumetric polymerization shrinkage: %. For notched Izod impactstrength: J/m. For tear strength: kN/m. In Tables I-IV, dashes (--)indicate that the component was absent or the value is not reportedhere. However, to be clear, all of Inks 1-14 are “according to thepresent invention” as broadly described herein. Additionally, Inks 1-14are particularly preferred embodiments of the present invention.

EXAMPLE 2 Variations in Amounts of Oligomeric Curable Material andAdditional Curable Material

Inks 1-3 in Table I were prepared according to the procedure inExample 1. The amount of the oligomeric curable material was varied from40 to 50 wt. %, while the amounts of cyclocarbonate(meth)acrylatemonomer and photoinitiator remained constant. The balance of the inkswas formed primarily from additional curable materials differing fromthe oligomeric curable material and the cyclocarbonate (meth)acrylatemonomer. The amount of additional curable material varied from 27 to 37wt. %. The oligomeric curable material in each of Inks 1-3 was a mixtureof aliphatic polyester urethane acrylate, aliphatic urethane diacrylate,and aliphatic urethane triacrylate in approximately equal amounts. Thecyclocarbonate (meth)acrylate in each of Inks 1-3 was a monomer havingthe structure of Formula (A2). The additional curable material in Inks1-3 was a combination of 2-pheoxyethyl acrylate, acryloyl morpholine,(5-ethyl-1,3-dioxan-5-yl)methyl acrylate, trimethylene glycoldimethacrylate (TEGDMA), and trimethyl cyclohexyl acrylate. Thephotoinitiator was Irgacure 819.

TABLE I Ink Compositions. Ink 1 Ink 2 Ink 3 Oligomeric Curable 40 45 50Material Cyclocarbonate 20 20 20 (meth)acrylate Monomer Additional 37 3227 Curable Material Photoinitiator 3 3 3 Volumetric — — — polymerizationshrinkage Notched Izod — 77 45 Impact Strength Tear Strength — 185 —

EXAMPLE 3 Variation of Oligomeric Curable Material Species

Inks 4-6 in Table II were prepared according to the procedure inExample 1. In Inks 4-6, the amounts of the oligomeric curable material,cyclocarbonate (meth)acrylate monomer, photoinitiator, and additionalcurable material remained substantially constant. Additionally, thechemical identities of the cyclocarbonate (meth)acrylate monomer andphotoinitiator remained the same. The types of monomeric curablematerial also remained the same in Inks 4-6. Specifically, thecyclocarbonate (meth)acrylate was a monomer having the structure ofFormula (A2). The photoinitiator was Irgacure 819. The additionalcurable material was a combination of two or more of 2-pheoxyethylacrylate, acryloyl morpholine, (5-ethyl-1,3-dioxan-5-yl)methyl acrylate,trimethylene glycol dimethacrylate (TEGDMA), and trimethyl cyclohexylacrylate.

However, the type or species of oligomeric curable material wasdifferent for each of Inks 4-6. In particular, the oligomeric curablematerials were as follows. Ink 4: a 15:15:20 mixture (by weight) of,respectively, aliphatic polyester urethane diacrylate having a T_(g) of−60° C. and a dynamic viscosity of 200,000 cP at 50° C.; polyesterurethane acrylate having a T_(g) of 79° C. and a dynamic viscosity of150,000 cP at 50° C.; and aliphatic urethane diacrylate having a T_(g)of 32° C. and a dynamic viscosity of about 24,000 cP at 50° C. Ink 5: a15:35 mixture (by weight) of, respectively, aliphatic polyester urethanediacrylate having a T_(g) of −60° C. and a dynamic viscosity of 200,000cP at 50° C.; and polyether urethane methacrylate having a T_(g) of 75°C. and a dynamic viscosity of about 6,800 cP at 60° C. Ink 6: onlypolyether urethane methacrylate having a T_(g) of 75° C. and a dynamicviscosity of about 6,800 cP at 60° C.

TABLE II Ink Compositions. Ink 4 Ink 5 Ink 6 Oligomeric 50 50 50 CurableMaterial Cyclocarbonate 20 20 20 (meth)acrylate Monomer Additional 27 2727 Curable Material Photoinitiator 3 3 3 Volumetric — — — polymerizationshrinkage Notched Izod 71 >153 104 Impact Strength Tear Strength — — 120

EXAMPLE 4 Variation of Additional Curable Material Species

Inks 7-9 in Table II were prepared according to the procedure inExample 1. In Inks 7-9, the amounts of the oligomeric curable material,cyclocarbonate (meth)acrylate monomer, photoinitiator, and additionalcurable material remained substantially constant. Moreover, the chemicalidentities of the oligomeric curable material, cyclocarbonate(meth)acrylate monomer, and photoinitiator remained the same.Specifically, the oligomeric curable material was a 15:15 mixture (byweight) of aliphatic polyester urethane diacrylate having a T_(g) of−60° C. and a dynamic viscosity of 200,000 cP at 50° C.; and polyesterurethane acrylate having a T_(g) of 79° C. and a dynamic viscosity of150,000 cP at 50° C. The cyclocarbonate (meth)acrylate was a monomerhaving the structure of Formula (A2). The photoinitiator was Igacure819.

However, the type or species of additional curable material wasdifferent for each of Inks 7-9. In particular, the additional curablematerials were as follows. Ink 7: a 5:27 mixture (by weight) of,respectively, 2-phenoxyethyl acrylate and(5-ethyl-1,3-dioxan-5-yl)methyl acrylate. Ink 8: a 5:27 mixture (byweight) of, respectively, isobornyl acrylate and(5-ethyl-1,3-dioxan-5-yl)methyl acrylate. Ink 9: a 5:5:22 mixture (byweight) of, respectively, 2-phenoxyethyl acrylate, isobornyl acrylate,and (5-ethyl-1,3-dioxan-5-yl)methyl acrylate.

TABLE III Ink Compositions. Ink 7 Ink 8 Ink 9 Oligomeric 45 45 45Curable Material Cyclocarbonate 20 20 20 (meth)acrylate MonomerAdditional 32 32 32 Curable Material Photoinitiator 3 3 3 Volumetric — —— polymerization shrinkage Notched Izod 77 52 70 Impact Strength TearStrength 185 — —

EXAMPLE 5 Variations in Amount of Cyclocarbonate (Meth)acrylate Monomer

Inks 10-14 were prepared according to the procedure in Example 1. InTable IV, the amount of cyclocarbonate (meth)acrylate monomer variedfrom 15 to 35 wt. %, while the chemical identity of this monomerremained the same (corresponding to the structure of Formula (A2)).Moreover, the amounts of oligomeric curable material, additional curablematerial, and photoinitiator remained within ranges described herein.

The oligomeric curable material in Ink 10 was a mixture of aliphaticpolyester urethane acrylate, aliphatic urethane diacrylate, andaliphatic urethane triacrylate. In Ink 11, the oligomeric curablematerial was a mixture of aliphatic urethane diacrylate, aliphaticurethane triacrylate, and polyester urethane acrylate. In Ink 12, it wasa mixture of aliphatic polyester urethane acrylate, aliphatic urethanediacrylate, and aliphatic urethane triacrylate in approximately equalamounts. The oligomeric curable material for Inks 13 and 14 waspolyester urethane acrylate.

The additional curable material in Inks 10-14 was a combination of2-pheoxyethyl acrylate, acryloyl morpholine,(5-ethyl-1,3-dioxan-5-yl)methyl acrylate, trimethylene glycoldimethacrylate (TEGDMA), and trimethyl cyclohexyl acrylate. Thephotoinitiator was Irgacure 819.

TABLE IV Ink Compositions. Ink 10 Ink 11 Ink 12 Ink 13 Ink 14 Oligomeric49 49 45 50 42 Curable Material Cyclocarbonate 15 20 25 30 35(meth)acrylate Monomer Additional 33 28 27 17 19.5 Curable MaterialPhotoinitiator 3 3 3 3 3.5 Volumetric — — — — — polymerization shrinkageNotched Izod 38 33 68 60 — Impact Strength Tear Strength — — — 93 —

As demonstrated by the data above, it is to be understood that inksdescribed and claimed herein are not limited to only the exactembodiments of Inks 1-14. Instead, based on the teachings of the presentdisclosure, other specific inks can be formulated by those of ordinaryskill in the art.

Some additional, non-limiting example embodiments are provided below.

Embodiment 1. An ink for use in a three-dimensional printing system, theink comprising:

20-60 wt. % oligomeric curable material;

15-50 wt. % cyclocarbonate (meth)acrylate monomer; and

0.1-5 wt. % photoinitiator, based on the total weight of the ink,

wherein the oligomeric curable material comprises one or moreethylenically unsaturated species having a molecular weight of500-6,000;

wherein the cyclocarbonate (meth)acrylate monomer has the structure ofFormula (A1):

wherein R₁ is selected from the group consisting of a linear or branchedC1-C6 alkylene moiety, an alkylene-carbonate moiety, an alkylene-estermoiety, and an alkylene-amide moiety ; and

wherein R₂ is H or CH₃.

Embodiment 2. The ink of Embodiment 1, wherein the oligomeric curablematerial comprises one or more ethylenically unsaturated species havinga dynamic viscosity of 125,000 to 250,000 cP at 50° C., when measuredaccording to ASTM D2983.

Embodiment 3. The ink of Embodiment 2, wherein the oligomeric curablematerial comprises one or more ethylenically unsaturated species havinga dynamic viscosity of 150,000 to 200,000 cP at 50° C., when measuredaccording to ASTM D2983.

Embodiment 4. The ink of any of the preceding Embodiments, wherein theoligomeric curable material comprises one or more aliphatic urethane(meth)acrylates.

Embodiment 5. The ink of any of the preceding Embodiments, wherein theoligomeric curable material is present in the ink in an amount of 25-50wt. %, based on the total weight of the ink.

Embodiment 6. The ink of any of the preceding Embodiments, wherein R₁ isa linear or branched C1-C4 alkylene moiety.

Embodiment 7. The ink of any of the preceding Embodiments, wherein R₂ isH.

Embodiment 8. The ink of any of the preceding Embodiments, wherein R₁ isCH₂ and R₂ is H.

Embodiment 9. The ink of any of the preceding Embodiments, wherein thecyclocarbonate (meth)acrylate monomer is present in the ink in an amountof 20-30 wt. %, based on the total weight of the ink.

Embodiment 10. The ink of any of the preceding Embodiments, wherein theink further comprises one or more additional curable materials differingfrom the oligomeric curable material and the cyclocarbonate(meth)acrylate monomer.

Embodiment 11. The ink of Embodiment 10, wherein the additional curablematerials comprise an additional monomeric curable material.

Embodiment 12. The ink of Embodiment 10, wherein the additional curablematerials comprise an additional oligomeric curable material.

Embodiment 13. The ink of any of the preceding Embodiments, wherein theink further comprises at least one colorant.

Embodiment 14. The ink of any of the preceding Embodiments, wherein theink further comprises at least one filler.

Embodiment 15. The ink of any of the preceding Embodiments, wherein theink further comprises at least one inhibitor, at least one stabilizingagent, or a combination thereof.

Embodiment 16. The ink of any of the preceding Embodiments, wherein thedynamic viscosity of the uncured ink is greater than 100 cP at 50° C.,when measured according to ASTM D2983.

Embodiment 17. The ink of Embodiment 16, wherein the dynamic viscosityof the uncured ink is greater than 100 cP and less than 5000 cP at 50°C., when measured according to ASTM D2983.

Embodiment 18. The ink of any of the preceding Embodiments, wherein theink, when cured, exhibits a volumetric polymerization shrinkage of nogreater than 5% compared to the ink when uncured, wherein the volumetricpolymerization shrinkage is measured according to ASTM D792.

Embodiment 19. The ink of any of the preceding Embodiments, wherein theink, when cured, exhibits a notched Izod impact strength of 50 to 200J/m when measured according to ASTM D256.

Embodiment 20. The ink of any of the preceding Embodiments, wherein theink, when cured, exhibits a tear strength of 20 to 200 kN/m whenmeasured according to ASTM D624.

Embodiment 21. A method of printing a three-dimensional articlecomprising:

selectively depositing layers of an ink in a fluid state onto asubstrate to form the three-dimensional article,

wherein the ink comprises the ink of any of Embodiments 1-20.

Embodiment 22. The method of Embodiment 21 further comprisingphotocuring the ink.

Embodiment 23. A method of printing a three-dimensional articlecomprising:

retaining an ink in a fluid state in a container;

selectively applying energy to the ink in the container to solidify atleast a portion of a first fluid layer of the ink, thereby forming afirst solidified layer that defines a first cross-section of thearticle;

raising or lowering the first solidified layer to provide a second fluidlayer of the ink at a surface of the fluid ink in the container; and

selectively applying energy to the ink in the container to solidify atleast a portion of the second fluid layer of the ink, thereby forming asecond solidified layer that defines a second cross-section of thearticle, the first cross-section and the second cross-section beingbonded to one another in a z-direction, wherein the ink comprises theink of any of Embodiments 1-20.

Embodiment 24. The method of Embodiment 23, wherein selectively applyingenergy to the ink in the container comprises photocuring the ink.

Embodiment 25. The method of Embodiment 23, wherein the method ofprinting has a print speed of 20-60 or 45-55 mm/hr.

Embodiment 26. A printed three-dimensional article formed from the inkof any of Embodiments 1-20.

All patent documents referred to herein are incorporated by reference intheir entireties. Various embodiments of the invention have beendescribed in fulfillment of the various objectives of the invention. Itshould be recognized that these embodiments are merely illustrative ofthe principles of the present invention. Numerous modifications andadaptations thereof will be readily apparent to those skilled in the artwithout departing from the spirit and scope of the invention.

The invention claimed is:
 1. An ink for use in three-dimensionalprinting, the ink comprising: 20-60 wt. % oligomeric curable material;15-50 wt. % cyclocarbonate (meth)acrylate monomer; and 0.1-5 wt. %photoinitiator, based on the total weight of the ink, wherein theoligomeric curable material comprises one or more ethylenicallyunsaturated species having a weight average molecular weight of500-6,000; wherein the cyclocarbonate (meth)acrylate monomer has thestructure of Formula (A1):

wherein R₁ is selected from the group consisting of a linear or branchedC1-C6 alkylene moiety, an alkylene-carbonate moiety, an alkylene-estermoiety, and an alkylene-amide moiety and R₂ is H or CH₃; and wherein theamounts of at least the oligomeric material, the cyclocarbonate, and thephotoinitiator are selected such that the ink, when cured, exhibits atear strength of 30 to 200 kN/m when measured according to ASTM D624. 2.The ink of claim 1, wherein the oligomeric curable material comprisesone or more ethylenically unsaturated species having a dynamic viscosityof 1,000 to 250,000 cP at 50° C., when measured according to ASTM D2983.3. The ink of claim 2, wherein the oligomeric curable material comprisesone or more ethylenically unsaturated species having a dynamic viscosityof 1,000 to 200,000 cP at 50° C., when measured according to ASTM D2983.4. The ink of claim 1, wherein the oligomeric curable material comprisesone or more aliphatic urethane (meth)acrylates.
 5. The ink of claim 1,wherein the oligomeric curable material is present in the ink in anamount of 25-50 wt. %, based on the total weight of the ink.
 6. The inkof claim 1, wherein R₁ is a linear or branched C1-C4 alkylene moiety. 7.The ink of claim 1, wherein R₂ is H.
 8. The ink of claim 1, wherein R₁is CH₂ and R₂ is H.
 9. The ink of claim 1, wherein the cyclocarbonate(meth)acrylate monomer is present in the ink in an amount of 20-30 wt.%, based on the total weight of the ink.
 10. The ink of claim 1, whereinthe ink further comprises one or more additional curable materialsdiffering from the oligomeric curable material and the cyclocarbonate(meth)acrylate monomer.
 11. The ink of claim 10, wherein the additionalcurable materials comprise an additional monomeric curable material. 12.The ink of claim 10, wherein the additional curable materials comprisean additional oligomeric curable material.
 13. The ink of claim 1,further comprising at least one colorant.
 14. The ink of claim 1,further comprising at least one filler.
 15. The ink of claim 1, furthercomprising at least one inhibitor, at least one stabilizing agent, or acombination thereof.
 16. The ink of claim 1, wherein the dynamicviscosity of the uncured ink is greater than 100 cP at 25° C., whenmeasured according to ASTM D2983.
 17. The ink of claim 16, wherein thedynamic viscosity of the uncured ink is greater than 100 cP and lessthan 5000 cP at 25° C., when measured according to ASTM D2983.
 18. Theink of claim 1, wherein the ink, when cured, exhibits a volumetricpolymerization shrinkage of no greater than 5% compared to the ink whenuncured, wherein the volumetric polymerization shrinkage is measuredaccording to ASTM D792.
 19. The ink of claim 1, wherein the ink, whencured, exhibits a notched Izod impact strength of 50 to 200 J/m whenmeasured according to ASTM D256.
 20. A method of printing athree-dimensional article comprising: selectively depositing layers ofan ink in a fluid state onto a substrate to form the three-dimensionalarticle, wherein the ink comprises the ink of claim
 1. 21. The method ofclaim 20 further comprising photocuring the ink.
 22. A method ofprinting a three-dimensional article comprising: retaining an ink in afluid state in a container; selectively applying energy to the ink inthe container to solidify at least a portion of a first fluid layer ofthe ink, thereby forming a first solidified layer that defines a firstcross-section of the article; raising or lowering the first solidifiedlayer to provide a second fluid layer of the ink at a surface of thefluid ink in the container; and selectively applying energy to the inkin the container to solidify at least a portion of the second fluidlayer of the ink, thereby forming a second solidified layer that definesa second cross-section of the article, the first cross-section and thesecond cross-section being bonded to one another in a z-direction,wherein the ink comprises the ink of claim
 1. 23. The method of claim22, wherein selectively applying energy to the ink in the containercomprises photocuring the ink.
 24. The method of claim 22, wherein themethod of printing has a print speed of 20-60 mm/hour.
 25. A printedthree-dimensional article formed from the ink of claim
 1. 26. The ink ofclaim 1, wherein the ink, when cured, exhibits a tear strength of 80 to200 kN/m when measured according to ASTM D624.
 27. The ink of claim 1,wherein the ink, when cured, is at least 70% cross-linked.